Surface Modification of Carbon Nanotubes as a Key Factor on Rheological Characteristics of Water-Based Drilling Muds

This study investigates the effect of functionalized Multi-Walled Carbon NanoTube (f-MWCNT) on rheological properties of water-based drilling muds. Functionalization of multi-walled carbon nanotube was performed by introducing a hydrophilic functional group onto the surface of nanotubes via acid treatment. In order to guarantee the results, X-ray fluorescence, transmission electron microscopy, and thermogravimetric analysis were performed on samples. Temperature and mud density variations were also considered along with the effect of f-MWCNT addition. Furthermore, a novel study was performed on the influence of the degree of functionalization on plastic viscosity and yield stress of drilling mud samples. The results obtained from this study revealed that the addition of f-MWCNT greatly affects the rheological characteristics of water-based drilling muds like plastic viscosity, apparent viscosity, yield stress, and thixotropic properties. Moreover, test results indicated that the shear stress versus shear rate diagram fitted well the Herschel-Bulkley rather than the Bingham plastic model.